Boron compounds have long been used in the wood preservation industry for the preservation of wood from termite attack. However, many boron compounds have a degree of solubility in water such that upon exposure of treated wood to environmental conditions, the compound can, under some conditions, leach from the wood, causing wood treated with boron compounds to demonstrate a preservation efficacy which is less than would be expected from the calculated retention immediately following treatment with the compound. For example, wood which has been exposed to damp environments is known to suffer from a reduced preservation efficacy, possibly due to leaching of the boron compound to the environment.